High energy tubular incandescent lamp having heat dissipative sleeves



NOV. 28, 1967 R @AY-[ON ET AL 3,355,613

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` ATTORNEY United States Patent Office 3,355,613 Patented Nov. Z8, 1967 3,355,613 HIGH ENERGY TUBULAR INCANDESCENT LAMP HAVING HEAT DISSIPATIVE SLEEVES David R. Dayton, Beverly, and Paul E. Gates, Danvers,

Mass., assignors to Sylvania Electric Products Inc., a

corporation of Delaware Filed Aug. 4, 1965, Ser. No. 477,155 5 Claims. (Cl. 313-40) This invention relates to incandescent electric lamps and more particularly to tubular lamps having high powered infrared or visible radiation.

Infrared lamps generally comprise a tubular envelope having lead-in Wires sealed in opposite ends of the envelope, and a helically coiled filament extending axially of the envelope and connected at each end to the corresponding lead-in wire. The radiation capacity and active length of present lamps is limited by the effects of heat which is convected or radiated into the seal region and which can cause destruction of the seal and consequent lamp failure. Present lamps are limited in capacity t about 200 Watts per inch up to an active length (filament length) of approximately 24 inches, and usually much less wattage for lamps longer than 24 inches.

It would be advantageous to have, and it is an object of the invention to provide, a tubular lamp of very high radiation capacity in which the seal regions are protected from excessive heat.

In accordance with the present invention, a tubular lamp is provided with a coaxial collar on each end thereof, having a greater cross sectional area than the envelope and fuse thereto near respective ends of the filament to provide a dissipation path to the environment and away from the seal region. The lamp may also have an elongated envelope between the seal and the filament to increase the conductive and radiative heat path, and a shield disposed orthogonal to the filament axis on each end thereof to reduce the amount of radiant heat from the filament reaching the seal.

The invention will be more fully understood from the following detailed description, taken in conjunction 'with the drawing, the single ligure of which is an elevation view, partly in section, of a tubular lamp according to the invention.

Referring to the drawing, there is shown a tubular lamp which includes an elongated tubular envelope 10 made of fused silica, such as quartz or Vycor, or other vitreous material, and lled with a suitable inert gas. A helically coiled filament 12 of refractory metal wire is mounted within and extends throughout most of the length of envelope 10, and is connected at each end to lead-in wires 14 which are suitably sealed in end portions 16 of the` envelope. Well known graded seals can be employed to match the coefficients of thermal expansion of the envelope glass and the sealing glass. The filament can be connected to the lead-in wires in any suitable manner, and is supported along its length in substantially coaxial relationship with envelope 10 by a plurality of spacers 18 fabricated of a refractory metal and which may be round, square, hexagonal or any other shape suitable to the task.

These lamps are generally employed as a source of high intensity infrared ener-gy, the radiation capacity of conventional lamps being limited by the amount of heat that can be suffered by the seal area without destroying the seal. Lamps constructed according to the present invention, however, have greater radiation capacities than conventional lamps due to the judicious employment of fused silica collars 20, of greater cross sectional area than that of envelope 10, each of which is fused or otherwise connected to the envelope near respective ends of filament 12 and which extend toward respective ends of envelope 10 in substantially coaxial spaced apart relationship therewith.

In operation, heat generated by filament 12 will radiate toward the lower temperature areas, including the seal region, and will also be conducted via lead-in wies 14 and envelope 10 to the seal region. By virtue of collar 20, however, some heat is transferred to the collar Which would otherwise have been transmitted to the seal. The collar is of larger cross sectional area than that of envelope 10 and is, therefore, an attractive heat sink for dissipating unwanted heat to the atmosphere. Heat sinking is further enhanced in practice by the use of metal clamps disposed around the collars by which the lamp is supported in its operating position.

The amount of heat reaching the seals is further reduced by shields 22, each disposed near a respective end of filament 12 and orthogonal thereto, and by the elongated envelope portions between the filament ends and the seals 4which increases the length of the heat path, thereby attenuating the heat intensity at the seals. Shields 22 are dimensioned to just fit within envelope 10 and can be a variety of shapes, such as round, hexagonal, etc. Still further heat dissipation can be provided, if desirable, by employing a water jacket around the envelope through which water or other suitable fluid can be circulated for cooling.

Lamps of the type described hereinabove are made in a variety of sizes and ratings to suit a particular purpose. By way of example, a typical lamp has been constructed according to the invention having a quartz envelope 39 inches long overall, with outside and inside diameters, respectively, of 25 and 22 millimeters. A tungsten lilament 25 inches long was employed and was connected to 1/s inch tungsten lead-in wires. rhe collar was 3% inches long and had respective outside and inside diameters of 35 and 33 millimeters. This lamp is energized by a 480 volt source and generates approximately 12,700 watts, which, for an active length of 25 inches, is about 500 Watts per inch; two and one-half times more power than conventional lamps of comparable size. In another lamp construction according to the invention, an active filament length of l5 inches produce 15,000 watts, or 1,000 watts per inch; a factor of five improvement over conventional lamps of comparable size.

The invention is not to be limited by what has been particularly shown and described, except as indicated in the appended claims.

What is claimed is:

1. A tubular incadescent lamp comprising, a sealed gasfilled tubular envelope of vitreous material, a lead-in wire extending through each end of said envelope and in sealing engagement therewith, a coiled filament extending substantially coaxially within said envelope and connected at each end to respective lead-in wires, and external collars of vitreous material each fused at one end to said envelope near respective ends of said filament, surrounding said envelope but spaced therefrom and eX- tending toward respective ends of said envelope.

2. A tubular incandescent lamp comprising, a hermetically sealed tubular envelope consisting essentially of fused silica, lead-in wires sealed through each end of said envelope, a coiled filament of refractory metal eX- tending substantially coaxially within said envelope and connected at each end to respective lead-in wires, a heat shield disposed near each end of said filament and orthogonal thereto, said envelope having an elongated heat path between the end of said filament and said sealed region, and first and second external collars of fused silica each fused to said envelope near a respective end of said filament, surrounding said envelope but spaced therefrom and extending coaxially therewith toward a respective end of said envelope.

3. A tubular incandescent lamp` comprising, a sealed gas-lled tubular envelope of fused silica, a lead-in wire extending through each end of said envelope and in sealing engagement therewith, a coiled filament extending substantially coaxially within said envelope and connected at each end to a respective lead-in wire, and first and second external collars of fused silica each disposed in spaced-apart coaxial realtion with said envelope between respective ends of said filament and respective ends of said envelope, the end of each collar near said filament being connected to said envelope.

4. In a tubular incandescent lamp which includes a silica, a lead-in wire sealed through each end of said envelope, and a coiled filament extending substantially coaxially Within said envelope and connected at each end to respective lead-in Wires, means for reducing the amount of heat transmitted to the sealed ends of said lamp comprising, first and second elongated external collars of fused silica each ydisposed in spaced-apart co'- axial relation with said envelope between respective ends of said filament and respective ends of said envelope, t'he end of each collar near said filament being connected to said envelope.

5. In a tubular incandescent lamp, the combination comprising: a tubular envelope of fused silica having a sealed end; yan externally extendig lead-in wire sealed through said sealed end of said envelope into the interior thereof; a coiled filament disposed within said envelope and connected at one end to said lead-in wire; an external heat-dissipating collar of fused silica coaxially disposed about said envelope, one end of said collar being fused to said envelope adjacent the end through which said lead-in Wire is sealed, the remainder of said collar being spaced therefrom and unattached to said envelope and having a larger diameter than said envelope and extending toward the sealed end thereof.

References Cited UNITED STATES PATENTS 2,097,679 11/ 1937 Swanson 313-26 2,400,081 5/1946 Ertel 313--40 2,966,602 12/1960 Waymouth 313-45 FOREIGN PATENTS 216,079 7/ 1958 Australia.

S. D. SCHLOSSER, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFCATE OF CORRECTION Patent No. 3,355,613 November 28, 1967 David R. Dayton et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the Said Letters Patent should read as corrected below.

Column 3, line 12, after "includes a" insert sealed gas-filled elongated tubular envelope of fused Signed and sealed this 3rd day of December 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. A TUBULAR INCANDESCENT LAMP COMPRISING, A SEALED GASFILLED TUBULAR ENVELOPE OF VITREOUS MATERIAL, A LEAD-IN WIRE EXTENDING THROUGH EACH END OF SAID ENVELOPE AND IN SEALING ENGAGEMENT THEREWITH, A COILED FILAMENT EXTENDING SUBSTANTIALLY COAXIALLY WITHIN SAID ENVELOPE AND CONNECTED AT EACH END TO RESPECTIVE LEAD-IN WIRES, AND EXTERNAL COLLARS OF VITREOUS MATERIAL EACH FUSED AT ONE END TO SAID ENVELOPE NEAR RESPECTIVE ENDS OF SAID FILAMENT, SURROUNDING SAID ENVELOPE BUT SPACED THEREFROM AND EXTENDING TOWARD RESPECTIVE ENDS OF SAID ENVELOPE. 